dsh-math-render

A DeepSeek Harness (dsh) plugin that renders LaTeX in the web GUI:

• Your own message bubble — $...$, $$...$$, \(...\) and \[...\] in a message you sent render as formulas, in place.
• Composer draft preview — while the draft contains a formula, a strip above the input renders it live. With no formula in the draft the strip does not exist at all.

Assistant replies already render through the shell's KaTeX pipeline; this plugin does not touch them.

Install

dsh plugin --profile web add dsh-math-render

Restart the harness afterwards (the profile's bundle list is read at boot), then reload the GUI page.

Installing from a checkout instead

dsh plugin --profile web add /path/to/dsh-math-render

Same mechanism: the package declares a dsh.bundle layer, so dsh plugin add records it in the profile and its row mounts at the next boot.

How it works

Seat	What it does	Why that seat
conversation.chat.node, keys user and steering, at priority: -1	Shadows the shipped user-bubble renderer. The bubble keeps its shipped shape — same DOM, same geometry, same attachments, same copy action. Only TeX runs are handed to the shell's own MarkdownText, the renderer assistant replies use	The slot registry projects one winner per cell in ascending priority order, so -1 outranks the shipped 0. The registry's own error text documents the route: register at a different priority to shadow it (lowest renders)
conversation.input.dock, id math-preview, order: 5	The draft preview strip above the composer	That seat is a session-scoped list seat rendered with the input snapshot (draft included), so no internal service has to be reached; order: 5 keeps it ahead of the shipped queue dock at 20

The host half is a package anchor plus one read-only diagnostic route. It holds no state and touches nothing at boot.

Behaviour

• A message without TeX renders exactly as the shipped bubble did. Prose still goes through the shell's plain-text projection, so it is not Markdown-ified: *, # and backticks keep their literal meaning.
• Backticks are the escape hatch. TeX inside a fenced code block or an inline code span stays literal, and so does \$.
• Currency is not mistaken for math. costs $5 and $10 stays prose: a closing $ glued to a digit is refused, as is space-padded content.
• Bad TeX is not hidden. It goes to the shell renderer, so a syntax error shows KaTeX's error output, exactly as in an assistant reply.
• A crashing renderer falls back to the shipped bubble. The slot boundary contains entry crashes and abdicates the entry from its cell, so the worst case is "no effect", not a broken transcript.
• No preview on the new-session hero composer. The host renders that seat only for a bound session; it appears once the first message puts you inside the conversation.

Limitations

• The bubble geometry is copied CSS. Those sheets are CSS modules whose hashed class names no out-of-tree bundle can resolve, and the client module table exposes no ui-chat component. An accurate restyle of the shell will not reach these declarations, so the bubble keeps the geometry of the build it was copied from. Colours, fonts and spacing ride --dsw-* / --dsh-* custom properties, which the shell still owns. Removing the plugin restores the shipped bubble exactly.
• The composer preview is a preview, not inline WYSIWYG. The composer is a Lexical editor and the plugin seams expose no inline widget. Typing $x^2$ renders in the strip above the input, not inside the editable area.
• dsh.bundle and a hand-written file:// row are mutually exclusive. Two active Loader sources for one package name is an error; install it one way.

Diagnostics

curl -s http://127.0.0.1:<port>/plugin/math-render/status
# {"plugin":"dsh-math-render","version":"1.0.0","mounted":true,"clientRegistered":true,"clientBundle":"…/client.js"}

Loopback Host only. mounted proves the row resolved; clientRegistered proves the browser half is in the client module graph. In the page console, document.querySelector('style[data-plugin-css="dsh-math-render/styles.css"]') is non-null once the browser half has loaded.

Tests

npm install
npm test

No harness, no browser, no network. 27 assertions over the tokenizer (delimiters, display math across lines, currency and code-span refusals, plus the invariant that segments must reconstruct the source exactly), the shapes both seats are registered with, the components (TeX routes to MarkdownText, a mathless message never reaches it, malformed nodes degrade instead of throwing, the preview's zero footprint), and — when the shell's own slot registry is reachable — the shadowing semantics, including that abdication hands the cell back to the shipped bubble.

Compatibility

Written and verified against dsh 0.1.5-rc.2 (client packages 0.1.5-rc.2, DSH Desktop 2.0.13). Seat names, priority shadowing, the projectUserText / MarkdownText / writeClipboard primitives, and the conversation.input.dock render props were read out of that version's sources. Newer shell versions may move any of them.

License

MIT